Chapter 23, Problem 23.11P

Interpretation Introduction

Interpretation:

Whether the aromatic ring in $\text{trifluoromethylbenzene }\left({\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{-CF}}_{\text{3}}\right)$ is activated or deactivated is to be determined.

Concept introduction:

Substituents that are electron donating, via either resonance or inductive effects, stabilize the arenium ion intermediate and increase the overall reaction rate, so they are activating. These groups also stabilize the ortho and para arenium ion intermediates better than they do the meta intermediate, so they are ortho/para directors. By the same token, substituents that destabilize the arenium ion intermediate by withdrawing electron density are deactivating groups. These groups destabilize the ortho and para intermediates more than they do the meta, making them meta directors.